Introduction

• Loss of sympathetic innervation to head and specifically to the eye; often unilateral.
• Cause: secondary to other disease process, eg perivascular injections, periorbital masses, cervical neck trauma, thoracic masses and guttural pouch abnormalities   Guttural pouch: empyema    Guttural pouch: mycosis  .
• Signs: ptosis , miosis, enophthalmos     , patchy head/neck sweating.
• Diagnosis: history, clinical signs.
• Treatment: directed at primary problem.
• Prognosis: guarded - related to primary problem.

Pathogenesis

Etiology

• Injury of the descending sympathetic fibers in the spinal cord due to neck trauma   Spinal cord: trauma  .
• Damage to cervical vagosympathetic trunk during intravenous   Intravenous catheterization  /intramuscular injections in the neck, or carotid artery catheterization   Carotid artery: intracarotid injection  .
• diseases of, or surgery on, the guttural pouch, especially guttural pouch mycosis   Guttural pouch: mycosis  or empyema   Guttural pouch: empyema  , especiallyStrep. equi.
• Cranial thoracic lesions, due to trauma/neoplasia/infection can affect the sympathetic chain.

Pathophysiology

• The sympathetic tract arises at T1-T3, it passes cranially through the cervicothoracic ganglion. The sympathetic fibers join the vagosympathetic tract following the path of the jugular vein to ascent up the neck to the cranial cervical ganglion situated just beneath the guttural pouch. These anatomical associations explain why just a diverse range of diseases can result in Horner's syndrome.
• Loss of sympathetic innervation to the head results in a combination of lesions, including abnormalities of the eye.
• Damage to the sympathetic innervation of the head   →   denervation of the dilator iris muscles, tarsal and orbital muscles and increased sensitivity of the skin blood vessels and neck sweat glands to circulating catecholamines.

Diagnosis

Treatment

Outcomes